Subject: Re: [PATCH iproute2] iproute2: Fix undeclared __kernel_long_t type build error in RHEL 6.8

From: Leon Romanovsky <[email-masked]>
Date: Sat, 2 Dec 2017 10:22:58 +0200

On Fri, Dec 01, 2017 at 08:56:24PM +0100, Michal Kubecek wrote:
> On Fri, Dec 01, 2017 at 08:48:07AM -0800, Stephen Hemminger wrote:
> > On Fri,  1 Dec 2017 13:04:51 +0200
> > Leon Romanovsky <[email-masked]> wrote:
> >
> > > From: Leon Romanovsky <[email-masked]>
> > >
> > > Add asm/posix_types.h header file to the list of needed includes,
> > > because the headers files in RHEL 6.8 are too old and doesn't
> > > have declaration of __kernel_long_t.
> > >
> > > In file included from ../include/uapi/linux/kernel.h:5,
> > >                  from ../include/uapi/linux/netfilter/x_tables.h:4,
> > >                  from ../include/xtables.h:20,
> > >                  from em_ipset.c:26:
> > > ../include/uapi/linux/sysinfo.h:9: error: expected specifier-qualifier-list before ‘__kernel_long_t’
> > >
> > > Cc: Riad Abo Raed <[email-masked]>
> > > Cc: Guy Ergas <[email-masked]>
> > > Signed-off-by: Leon Romanovsky <[email-masked]>
> >
> > I see the problem, but the solution of dragging in posix_types.h
> > would be too much of a long term maintenance issue.
> > All the headers in uapi are regularly generated from upstream
> > kernel headers; I don't want to start making exceptions.
> >
> > Is it just the xtables stuff (which has always been problematic)?
>
> Actually, the only place where __kernel_long_t and __kernel_ulong_t
> appear is struct sysinfo in include/uapi/linux/sysinfo.h and this
> structure isn't even used anywhere in iproute2 source (not even in the
> include/uapi/linux/kernel.h file which includes <linux/sysinfo.h>).
>
> So one could work around the problem by defining _LINUX_SYSINFO_H but
> that seems a bit dirty hack.

It is too dirty :). It can cause to completely unpredictable compilation
failures in the future, which won't be easy to track down.

> Michal Kubecek